1. Field of the Invention
The present general inventive concept relates to an image forming apparatus and a developer level calculating method of the same, and more particularly, to an image forming apparatus which includes a developer bottle to supply a developer and a developer level calculating method of the same.
2. Description of the Related Art
In general, an image forming apparatus scans a beam onto a photosensitive body electrified to a predetermined electric potential to form an electrostatic latent image corresponding to image data, develops the electrostatic latent image into a visible image by using a developer, and transfers and fuses the developed image on a printing medium to form an image thereon.
The image forming apparatus includes a developing unit which supplies a developer onto the photosensitive body, and may include a variety of methods so as to compliment a developer in the developing unit. Among these methods is known a method in which a developer bottle which contains a developer is separately provided to supply the developer to the developing unit.
In a conventional image forming apparatus, a developer level inside the developing unit is displayed to a user after image data is printed so that the user can predict a replacing time of the developing unit and determine the amount of image data to apply a printing signal. For this purpose, in the conventional image forming apparatus, the number of reference printing dots capable of printing per reference developer capacity is preset, and a developer level on the basis of the number of the reference printing dots is calculated.
However, even though the developer level is displayed being left to the user on the basis of the number of the printing dots, in reality there may be insufficient developer left inside the developing unit, thereby causing a problem that printing suddenly stops before completion of printing an image.
That is, as illustrated in FIG. 1, since the inclination of a first graph A in which a developer level is calculated on the basis of the number of printing-possible dots and a second graph B which illustrates a real developer level is different from each other, there is no developer left in the developing unit in reality in the case that ten percent of developer level is left in the first graph A (refer to a point X). At this time, if a user recognizes that there is enough developer remained and applies a printing signal, a developer replacing message is suddenly displayed to cause inconvenience to the user. That is because there is generated a difference in the amount of the developer provided on one dot due to a printing environment, the kind of a printing medium, temperature and humidity of an environment where the image forming apparatus is located, a developing voltage, a transferring voltage, and the like.
Also, in the case of an image forming apparatus in which the developer bottle and the developing unit are provided separately, a developer level sensor should be installed on the side of a developing roller because the developer level sensor can not be structurally installed on the side where the developer is supplied from the developer bottle. In this case, the developer level inside the developer bottle can not be accurately sensed on the side of the developing roller, thereby causing difficulty in calculating an accurate developer level.